With such blocking means which are immobilized on the tube plate, it is sometimes difficult to carry out the necessary maintenance operations at this plate, in particular in its surface which points towards the inside of the steam generator, for cleaning the tube plate or for checking the tubes and especially their linkage with the plate. Furthermore, in certain solutions in which the tube plate is equipped with a continuous blow down device, including in particular a pipeline parallel to the plate and pierced with holes distributed over its length for continuous sampling of water through this plate, the presence of these means may constitute a problem for obtaining optimal operation.
By way of example, in order to produce such a blow down system, it is possible to employ the arrangements described in Applicant's FR-A-92 07903, filed Jun. 26, 1992, in which these blow down means include at least one passage through the tube plate, through which an opening emerges on the upper face of this plate in the central region, this opening communicating with drainage means situated outside the casing of the generator.